تفاعلات البنزين-sulfonation-nitration-bromination-friedel crafts acylation and alkylation

Sulfonation
*Sulfnation of benzene* involves the introduction of a sulfonic acid group (-SO3H) into the benzene ring. This reaction is typically carried out using concentrated sulfuric acid (H2SO4) or fuming sulfuric acid (H2SO4 + SO3). The mechanism involves the formation of the electrophile sulfur trioxide (SO3), which then reacts with benzene to form benzenesulfonic acid.
Nitration
*Nitration of benzene* introduces a nitro group (-NO2) into the benzene ring. This reaction is usually performed with a mixture of concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4). The sulfuric acid acts as a catalyst, generating the nitronium ion (NO2+), which is the active electrophile that reacts with benzene to form nitrobenzene.
Bromination
*Bromination of benzene* adds a bromine atom to the benzene ring. This reaction requires a catalyst such as iron(III) bromide (FeBr3) to polarize the bromine molecule (Br2), creating a more reactive electrophile (Br+). The electrophilic bromine then substitutes one hydrogen atom in the benzene ring, forming bromobenzene.
Hydrogenation
*Hydrogenation of benzene* involves the addition of hydrogen atoms to the benzene ring, converting it into cyclohexane. This reaction typically requires a catalyst such as platinum, palladium, or nickel and is carried out under high pressure and temperature. Unlike the other reactions, hydrogenation completely reduces the aromatic ring, losing its aromatic properties.
Friedel-Crafts Acylation
*Friedel-Crafts acylation* introduces an acyl group (RCO-) into the benzene ring using an acyl chloride (RCOCl) and a Lewis acid catalyst such as aluminum chloride (AlCl3). The catalyst helps generate the acylium ion (RCO+), which is the electrophile that reacts with benzene to form a ketone, typically an aryl ketone.
Friedel-Crafts Alkylation
*Friedel-Crafts alkylation* introduces an alkyl group (R-) into the benzene ring using an alkyl halide (R-X) and a Lewis acid catalyst such as aluminum chloride (AlCl3). The catalyst generates a carbocation (R+), which acts as the electrophile that reacts with benzene to form an alkylbenzene. This reaction is useful for synthesizing various substituted aromatic compounds but can sometimes lead to polyalkylation or rearrangement of the alkyl group.

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